Francisco Liriano said he worked hard this offseason to perfect a tweak in his delivery. Manager Clint Hurdle said he has watched a lot of tape and still can't see a difference.

The difference in the results, however, is undeniable.

Liriano has been dominant this season and continued that early trend by striking out nine batters in seven scoreless innings to lead the Pirates to a 1-0 victory against the Chicago Cubs Wednesday night at PNC Park.

Since returning from the disabled list May 11, Liriano is 3-0 in three starts. He missed the first month and a half of the season after fracturing the humerus bone in his right, non-throwing arm in December.

He allowed two hits and walked one Wednesday night in his sharpest outing.

Liriano credits his improved command with a change he made in his throwing motion this offseason, moving his arm slot closer to his body and throwing the ball over his head.

"I'm just going over my head and not trying to overthrow," he said.

"Sometimes, I overthrow when I get into trouble. Other than that, I'm just trying to hit my spots. That makes the difference, right there."

Liriano has posted a 1.00 ERA in 18 innings, striking out 25 batters -- a rate of 12.5 strikeouts per nine innings. His command, a concern entering the season, is much improved.

"When he gets ahead with his fastball and he's close to the plate with his fastball, his other stuff plays up dramatically," Hurdle said.

Liriano deftly commanded the strike zone while cruising through the Cubs batting order, striking out at least one batter every inning he pitched. He threw 91 pitches, 59 for strikes.

"When he's had fastball command, those are the games that are electric for him," Hurdle said.

The Cubs' Jeff Samardzija, was nearly as brilliant. The tall right-handed pitcher struck out eight and allowed one earned run on three hits over seven innings. But that one run was enough to beat him and the Cubs with Liriano on the mound.

Samardzija always has pitched well against the Pirates, entering the game with a career 4-0 record and 0.92 ERA in 14 appearances, three of them starts.

In his previous start against the Pirates on opening day, he allowed two hits over eight scoreless innings.

This time, Samardzija (2-6) threw 111 pitches, 73 for strikes. He walked one.